Topological edge states in dipolar zig-zag stripes

TL;DR

This paper investigates topological magnon edge states in dipolar zig-zag chains, revealing how lattice geometry and dipolar interactions induce non-trivial band topology and edge mode behavior in 2D magnetic systems.

Contribution

It demonstrates the emergence of topologically non-trivial magnon bands in dipolar zig-zag lattices and how band topology switches with lattice parameter adjustments.

Findings

Topological magnon bands arise in dipolar zig-zag chains.

Band touching causes Chern number exchange and edge mode reversal.

Topological features persist with truncated dipolar interactions.

Abstract

We study the magnon spectrum of stacked zig-zag chains of point magnetic dipoles with an easy axis. The anisotropy due to the dipolar interactions and the two-point basis of the zig-zag chain unit cell combine to give rise to topologically non-trivial magnon bands in 2D zig-zag lattices. Adjusting the distance between the two sublattice sites in the unit cell causes a band touching, which triggers the exchange of the Chern numbers of volume bands switching the sign of the thermal conductivity and the sense of motion of edges modes in zig-zag stripes. We show that these topological features survive when the range of the dipolar interactions is truncated up to the second nearest neighbors.